Disclosed in the present invention are a deuterated dipeptide boronic acid or an ester compound thereof, or a crystalline form, pharmaceutically acceptable hydrate or solvate thereof, the structure thereof being shown in formula (a), wherein: R 1, R2, R3, R4, R5, and R6 are independently selected from hydrogen, deuterium, or a halogen, or one of a plurality of deuterated or fully deuterated C1-C4 alkyl groups; and at least one of R1, R2, R3, R4, R5, or R6 is deuterated or is deuterium. The compound of the present invention can effectively inhibit proteasomes, and can effectively treat or prevent cancer, cardiovascular disease, inflammation, immune disease, kidney disease, angiogenesis or prostate disease.